On the eve of a visit by Pope Francis to Japan, activists called Friday on the government to declare a moratorium on executions as part of an Olympic truce to mark Tokyo 2020.
The pope is expected to shine a spotlight on the death penalty in Japan, where it enjoys considerable popular support despite criticism from rights groups.
He may meet Iwao Hakamada, who spent nearly 50 years on death row after being accused of robbing and murdering his boss along with his boss's wife and two teenage children, before burning down their house.
Hakamada, who is waiting for a Supreme Court decision over a possible retrial, was freed from prison in 2014 decades after doubts emerged about his guilt. He has been invited to attend a Mass held by the pontiff, but it is unclear whether the two men will meet.
Mario Marazziti, the co-founder of the World Coalition Against the Death Penalty, told Japanese MPs and reporters that he was calling for "an Olympic truce, a 2020 moratorium in the year of the Olympic Games."